CN110676916B

CN110676916B - Self-adaptive charger

Info

Publication number: CN110676916B
Application number: CN201910592439.0A
Authority: CN
Inventors: 吴上林; 方胜贤
Original assignee: Schneider Electric IT Corp
Current assignee: Schneider Electric IT Corp
Priority date: 2018-07-03
Filing date: 2019-07-03
Publication date: 2024-04-23
Anticipated expiration: 2039-07-03
Also published as: EP4280422A3; EP3591801A1; US20200014237A1; US11011926B2; EP4280422A2; CN110676916A; EP3591801B1

Abstract

In accordance with at least one aspect of the present disclosure, a method of operating an Uninterruptible Power Supply (UPS) is provided. The method comprises the following steps: in a first mode of operation, receiving AC power at an input of the UPS; in the first mode, providing the AC power to a charger and a clamp charger circuit; charging a UPS battery of the UPS with a first charging current from at least a portion of the AC power source by the charger in the first mode; charging, by the clamp charger circuit in the first mode, the UPS battery with a second charging current from at least a portion of the AC power source; providing output power from the UPS battery at an output of the UPS in a second mode of operation; and charging the UPS battery with a third charging current through the clamp charger circuit in the second mode.

Description

Self-adaptive charger

Technical Field

At least one example in accordance with the invention generally involves a plurality of clamping circuits.

Background

Power devices using, for example, uninterruptible power supplies (uninterruptible power supply, UPS) are known to provide regulated uninterruptible power supply sources for sensitive and/or critical loads (e.g., computer systems and other data processing systems). Known uninterruptible power supplies include online (on-line) UPS, offline (offline) UPS, online interactive (LINE INTERACTIVE) UPS, and others. The online UPS provides regulated AC power as well as backup AC power when a primary source of AC power is interrupted. Offline UPSs typically do not provide regulation of the input AC power, but provide backup AC power when the AC power mains supply is interrupted. The online interactive UPS is similar to the offline UPS in that the online interactive UPS and the offline UPS switch to battery power when a power outage occurs, but typically also include a multi-tap transformer (multi-tap transformer) for regulating the output voltage provided by the UPS.

When mains power is available, a conventional offline UPS typically connects a load directly to the mains power. The conventional offline UPS also includes a charger that uses the mains to charge a backup power source (e.g., a battery). When mains is insufficient to power the load, the offline UPS operates a DC-AC inverter to convert DC power from the backup power source to the desired AC power, which is provided to the load.

Disclosure of Invention

In accordance with at least one aspect of the present invention, a method of operating an Uninterruptible Power Supply (UPS) is provided. The method comprises the following steps: in a first mode of operation, receiving AC power at an input of the UPS; in the first mode of operation, providing the AC power to a charger and a clamp charger circuit; charging a UPS battery of the UPS with a first charging current from at least a portion of the AC power source by the charger in the first mode of operation; charging the UPS battery with a second charging current from at least a portion of the AC power source by the clamp charger circuit in the first mode of operation; providing output power from the UPS battery at an output of the UPS in a second mode of operation; and charging the UPS battery with a third charging current by the clamp charger circuit in the second mode of operation.

In some embodiments, the method further comprises: an indication parameter of the first charging current and the second charging current in the first operating mode is sensed by a voltage regulator. In one embodiment, the method further comprises: generating a plurality of feedback signals by the voltage regulator based on the sensed parameters, and controlling the clamp charger circuit based on the plurality of feedback signals. In some embodiments, the method further comprises: the second charging current and the third charging current are regulated by the clamp charger circuit based on the plurality of feedback signals.

In one embodiment, the method further comprises: in the second mode of operation, a power source is received at the output of the UPS. In some embodiments, receiving power at the output of the UPS includes receiving power discharged from a load capacitor. In an embodiment, charging the UPS battery includes charging the UPS battery with the third charging current from at least a portion of the output power source.

According to one embodiment, an Uninterruptible Power Supply (UPS) system is provided. The UPS system includes an input configured to receive an input AC power source; an output configured to provide output AC power to a load; a battery charger coupled to the input and configured to be coupled to a battery; the battery charger is configured to receive a first portion of the input AC power from the input in a first mode of operation; and in the first mode of operation, providing a first charging current to the battery, the first charging current from the first portion of the input AC power source. The UPS system further includes a clamp charger circuit coupled to the output and the battery, the clamp charger circuit configured to receive a second portion of the input AC power from the input in the first mode of operation; providing a second charging current to the battery in the first mode of operation, the second charging current from the second portion of the input AC power source, providing power from the battery to the load in a second mode of operation; and in the second mode of operation, charging the battery.

In an embodiment, the clamp charger circuit is further configured to receive power from a load capacitor at the output in the second mode of operation. In some embodiments, the UPS system includes a voltage regulator coupled to the battery charger and the clamp charger circuit. In an embodiment, the voltage regulator is configured to sense an indicative parameter of the first charging current and the second charging current in the first mode of operation. In an embodiment, the voltage regulator is further configured to generate a plurality of feedback signals based on the sensed parameter and to communicate the plurality of feedback signals to the clamp charger circuit. In some embodiments, the clamp charger circuit is a DC/DC flyback converter.

In one embodiment, the DC/DC flyback converter includes an input configured to receive an input power supply; an output configured to be coupled to the battery; a transformer coupled between the input and the output, the transformer comprising a primary winding; a switch coupled in series with the primary winding; at least one optocoupler is configured to be coupled to the voltage regulator; and a pulse width modulation controller coupled to the at least one optocoupler and to the switch. In some embodiments, the PWM controller is configured to receive the plurality of feedback signals from the at least one optocoupler; generating a plurality of switching signals based on the plurality of feedback signals; and providing the plurality of switching signals to the switch to control a current through the primary winding. In some embodiments, controlling the current through the primary winding includes controlling an output current provided by the transformer to the output.

According to one embodiment, an Uninterruptible Power Supply (UPS) system is provided. The UPS system includes an input configured to receive an input AC power source; an output configured to provide output AC power to a load; a battery charger coupled to the input and configured to be coupled to a battery, the battery charger configured to receive a first portion of the input AC power from the input in a first mode of operation; and in the first mode of operation, providing a first charging current to the battery, the first charging current from the first portion of the input AC power source; a clamp charger circuit coupled to the output and the battery; and a plurality of means for charging charge the battery using the clamp charger circuit in the first mode of operation.

In one embodiment, the UPS system further includes means for receiving DC power from the load in a second mode of operation. In some embodiments, the means for charging the battery includes means for receiving, in the first mode of operation, a second portion of the input AC power from the input and, in the first mode of operation, providing a second charging current to the battery, the second charging current from the second portion of the input AC power. In an embodiment, the UPS system includes a plurality of means for providing, in the second mode of operation, a third charging current is provided to the battery, the third charging current from the battery.

Drawings

Various aspects of at least one embodiment are discussed below with reference to the accompanying drawings, which are not drawn to scale. The accompanying drawings are included to provide a further understanding of the description and embodiments of the various aspects and are incorporated in and constitute a part of this specification and are not intended as a definition of the limits of any particular embodiment. The remainder of the drawings and description serve to explain the principles and operation of the various aspects and embodiments described and claimed. In the drawings, identical components or nearly identical components that are illustrated in various figures are represented by like numerals. For purposes of clarity, not every component may be labeled in every drawing. In the figure:

FIG. 1 is a block diagram of a conventional offline UPS;

FIG. 2 illustrates a block diagram of an offline UPS, according to one embodiment;

FIG. 3 illustrates a process by which a UPS determines an operational mode;

FIG. 4 is a block diagram of the offline UPS in a standby mode of operation standby mode of operation according to one embodiment;

FIG. 5 illustrates a block diagram of the offline UPS in a mains operation mode (line mode of operation), according to one embodiment;

FIG. 6 illustrates a block diagram of the offline UPS in a battery mode of operation (battery mode of operation), according to one embodiment;

FIG. 7 illustrates a block diagram of a clamp charger circuit, according to one embodiment;

FIG. 8 depicts a circuit diagram of the clamp charger circuit, according to one embodiment; and

Fig. 9 shows various graphs of UPS measurement data.

Detailed Description

The examples of methods and systems discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The methods and systems are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. The examples of specific implementations provided herein are for illustrative purposes only and are not intended to be limiting. In particular, acts, components, or features discussed in connection with any one or more examples or embodiments are not intended to be excluded from a similar role in other examples.

Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any reference herein to an example, embodiment, component, element, or act of a system and method in the singular can also include an embodiment comprising a plurality of embodiments, and any reference herein to any embodiment, component, element, or act in the plural can also include an embodiment comprising only the singular. References in the singular or plural are not intended to limit the presently disclosed systems or methods, their components, acts, or elements. As used herein, "comprising," "including," "having," "containing," "involving (involving)" and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The reference "or" may be construed as inclusive such that any item described using the "or" may indicate any one of a single described item, more than one described item, and all described items. Furthermore, if a term usage between the present document and a document incorporated by reference into the present document is inconsistent, the term usage incorporated in the feature is complementary to the present document; for irreconcilable differences, it is the usage of the terms in this document that controls.

Embodiments of the present disclosure generally refer to a plurality of clamping circuits implemented in a plurality of Uninterruptible Power Supplies (UPSs). For example, it is described in U.S. patent application Ser. No. 15/042,444, filed on even date 2016, 2/12, the entire contents of which are incorporated herein by reference, that a clamp circuit can be implemented in a UPS. The clamp circuit is typically configured to boost the efficiency of the UPS by recycling power from a load capacitor (Xcap ").

Fig. 1 illustrates an example of a conventional offline UPS (generally indicated at 100) coupled to a load 122. The UPS 100 includes an input 102, an output 104, a charger 106, a voltage regulator 108, a battery 110, a relay 112, a clamp 114, an inverter 116, a reference terminal 118 (e.g., a ground terminal), and a controller 120. The load 122 includes a load capacitor 124.

The input 102 is coupled to the charger 106, the relay 112, and the reference terminal 118. The output 104 is coupled to the relay 112, the reference terminal 118, and the load 122. The charger 106 is coupled to the input 102, the voltage regulator 108, and the battery 110, and the charger 106 is communicatively coupled (communicatively coupled) to the controller 120. The voltage regulator 108 is coupled to the charger 106, the battery 110, and the clamp 114, and the voltage regulator 108 is communicatively coupled to the controller 120. The battery 110 is coupled to the charger 106, the voltage regulator 108, the clamp 114, the inverter 116, and the reference terminal 118.

The relay 112 is coupled to the input 102, the output 104, and the inverter 116, and the relay 112 is communicatively coupled to the controller 120. The clamp 114 is coupled to the voltage regulator 108, the battery 110, and the inverter 116, and the clamp 114 is communicatively coupled to the controller 120.

The inverter 116 is coupled to the battery 110, the relay 112, the clamp 114, and the reference terminal 118, and the inverter 116 is communicatively coupled to the controller 120. The reference terminal 118 is coupled to the input 102, the output 104, the battery 110, and the inverter 116. The controller 120 is configured to be communicatively coupled to the charger 106, the voltage regulator 108, the relay 112, the clamp 114, and the inverter 116.

The UPS 100 is generally configured to operate in one of at least two modes of operation, including a line mode (line mode) and a battery mode (battery mode). The mode of operation of the UPS 100 depends on a quality level (e.g., from a utility mains) AC power supply of the AC power received at the input 102

For example, if the controller 120 determines that the AC power received at the input 102 is acceptable (i.e., within a specified range of acceptable electrical parameters), the UPS 100 may be configured to operate in the utility mode. In other cases, the UPS 100 may be configured to operate in the battery mode if the controller 120 determines that the AC power received at the input 102 is not acceptable (i.e., not within a specified range of acceptable electrical parameters).

In the mains mode, the controller 120 drives the relay 112 to connect the input 102 to the output 104. The input 102 receives AC power from an external power source (e.g., from a mains AC power supply) and provides the received power to the output 104 and to the charger 106. The output 104 receives the power from the input 102 and provides the power to the load 122. The charger 106 receives the AC power from the input 102 and charges the battery 110 with the AC power. The voltage regulator 108 senses an electrical parameter (e.g., including a voltage parameter) of the charger 106 output and adjusts the charger 106 output based on the sensed electrical parameter.

The charger 106 may be rated for a particular charging power level to meet a maximum allowable battery recharging time specified by the designer of the UPS 100. For example, where the battery 110 has a particular energy storage capacity, the designer may specify that it must be fully recharged after no more than 12 hours of charging. In some examples, this design constraint requires that a charging power level rated by the charger 106 be approximately 15 watts.

In the battery mode, no acceptable AC power is available at the input 102. Thus, no AC power is provided from the input 102 to the output 104 or the charger 106. The charger 106 stops charging the battery 110 and the battery 110 discharges the stored DC power to the inverter 116. The inverter 116 converts the received DC power to AC power and provides the AC power to the output 104 through the relay 112 to provide power to the load 122.

In some examples, the load 122 may include a load capacitor 124 that stores reactive power (reactive power). The load capacitance may be considered undesirable because if the stored reactive power is not used to perform useful work, the power source may be wasted (e.g., as heat dissipation), thereby reducing the efficiency of a UPS supplying power to the load. To boost UPS efficiency, some conventional inverters (e.g., the inverter 116) may be configured to recycle the reactive power stored in the load capacitor 124 during the battery mode of operation.

For example, the inverter 116 may be configured to maintain an output voltage of the inverter 116 at 0 to discharge the reactive power stored in the load capacitor 124 to the inverter 116. The inverter 116 provides the discharged reactive power to the clamp 114, and the clamp 114 charges the battery 110 with the recycled reactive power. Accordingly, the efficiency of the UPS100 may be improved by recirculating the reactive power stored by the load capacitance 124 and charging the battery 110 with the recirculated reactive power.

Because the UPS 100 does not recycle the reactive power stored in the load capacitance 124 during the mains mode of operation, the clamp 114 does not charge the battery 110 during the mains mode of operation. Conversely, the charger 106 is activated only during the mains mode of operation, and the charger 106 is typically required to recharge the battery 110 within a specified maximum amount of time as discussed above.

In at least some embodiments discussed herein, a clamp circuit of an offline UPS charges a UPS battery in parallel with a primary battery charger during a mains mode of operation. Because the clamp circuit provides a portion of the battery charger power supply, the power rating (power rating) of the primary battery charger may be reduced. Reducing the power rating of the primary battery charger enables a smaller and cheaper charger while still fully recharging the UPS battery within a specified maximum amount of time.

Fig. 2 illustrates a block diagram of a UPS 200, the UPS 200 configured to be coupled to the load 122, according to one embodiment. The UPS 200 includes an input 202, an output 204, a charger 206, a voltage regulator 208, a battery 210, a relay 212, a clamp charger circuit 214, an inverter 216, a reference terminal 218 (e.g., a ground terminal), and a controller 220. The UPS 200 is similar to the UPS except that the clamp circuit 114 is replaced with the clamp charger circuit 214. The load 122 includes the load capacitance 124.

The input 202 is coupled to the charger 206, the relay 212, the reference terminal 218, and in some embodiments, the input 202 is coupled to an external AC power source, such as a mains power supply (not shown). The output 204 is coupled to the relay 212, the reference terminal 218, and the load 122. The charger 206 is coupled to the input 202, the voltage regulator 208, and the battery 210, and the charger 106 is communicatively coupled to the controller 220. The voltage regulator 208 is coupled to the charger 206 and the clamp charger circuit 214, and the voltage regulator 208 is communicatively coupled to the controller 220. The battery 210 is coupled to the charger 206, the clamp charger circuit 214, and the reference terminal 218, and the battery 210 is communicatively coupled to the controller 220. Although the battery 210 is depicted in fig. 2 as being internal to the UPS 200, in alternative embodiments, the battery 210 may be external to the UPS 200.

The relay 212 is coupled to the input 202, the output 204, and the inverter 216, and the relay 112 is communicatively coupled to the controller 220. The clamp charger circuit 214 is coupled to the output 204, the voltage regulator 208, the battery 210, and the relay 212, and the clamp charger circuit 214 is communicatively coupled to the controller 220. The inverter 216 is coupled to the battery 210 and the relay 212, and the inverter 216 is communicatively coupled to the controller 220. The reference terminal 218 is coupled to the input 202, the output 204, and the battery 210.

The input 202 is typically configured to receive power from an external power supply, such as a mains power supply (not shown). The input 202 provides the received power to the charger 206 and through the relay 212 to the output 204. The output 204 is generally configured to receive power from the relay 212 and provide the received power to the load 122.

In the mains mode of operation, the relay 212 connects the input 202 to the output 204 to provide power to the output 204. In the battery mode of operation, the relay 212 connects the inverter 216 to the output 204 to provide power to the output 204. In some embodiments, during the battery mode of operation, the load 122 may discharge reactive power stored in the load capacitance 124 to the output 204.

The charger 206 is generally configured to receive power from the input 202 and to charge the battery 210 using the received power. More specifically, the charger 206 may be configured to provide a constant charging current to the battery 210 at a constant voltage. The voltage regulator 208 is generally configured to detect an output of the charger 206 and an output of the clamp charger circuit 214 and provide a plurality of voltage feedback signals indicative of the outputs of the charger 206 and the clamp charger circuit 214. The battery 210 is generally configured to store power provided by the charger 206 and the clamp charger circuit 214 and discharge the stored power to the inverter 216.

The relay 212 is generally configured to connect the output 204 to one of the input 202 and the inverter 216. For example, the relay 212 may be configured to connect the output 204 to the input 202 in a mains mode of operation and may be configured to connect the output 204 to the inverter 216 in a battery mode of operation. The clamp charger circuit 214 is generally configured to provide recirculated load reactive power to the battery 210 in a battery mode of operation and to provide a charging current to the battery 210 in a utility mode of operation.

The inverter 216 is generally configured to provide power from the battery 210 to the output 204 in a battery mode of operation. For example, in the battery mode of operation, the inverter 216 may be configured to receive DC power from the battery 210 storage, convert the DC power to AC power, and provide the AC power to the output 204 via the relay 212. The controller 220 is generally configured to exchange a plurality of control and communication signals with a plurality of components of the UPS 200.

In operation, the UPS 200 is generally configured to operate in one of three modes of operation, including a standby mode of operation, a utility mode of operation, and a battery mode of operation. In at least one embodiment, the controller 220 is configured to receive measurement data (e.g., including input voltage measurement data, input current measurement data, etc.), analyze the measurement data, and select an operating mode based on the results of the analysis. The controller 220 may then control the various components of the UPS 200 to be consistent with the mode of operation selected.

Fig. 3 illustrates a process 300 for the UPS 200 to determine an operational mode. For example, in some embodiments, the process 300 may be performed by the controller 220. At act 302, the process 300 begins. At act 304, a determination is made as to whether power is to be provided to the output 204. For example, if the output 204 is not connected to a load, or if the load is powered down, the controller 220 may determine not to provide power to the output 204.

If no power is provided to the output 204 (no at 304), the process 300 continues to act 306. At act 306, a standby mode is entered, as discussed in more detail below with reference to FIG. 4. The process 300 continues to act 308 and the process 300 ends.

In other cases, if power is provided to the output 204 (304 yes), the process 300 continues to act 310. At act 310, an evaluation is made as to whether the input power provided to the input 202 is acceptable. An acceptable power source may be defined as a power source having parameters within a particular range. For example, a power supply having a sine wave pattern may be considered acceptable if the voltage of the sine wave pattern does not deviate more than a threshold from an ideal sine wave pattern having approximately the same target frequency, phase, and amplitude.

If the power at the input 202 is not acceptable (310 no), the process 300 continues to act 312. At act 312, a battery mode is entered, as discussed in more detail below with respect to FIG. 6. The process 300 continues to act 308 and the process 300 ends. In other cases, if the power at the input 202 is acceptable (yes 310), the process 300 continues to act 314. At act 314, a mains mode is entered, as discussed in more detail below with reference to FIG. 5. The process 300 continues to act 308 and the process 300 ends.

The standby operation mode will now be described with reference to fig. 4. Fig. 4 illustrates the UPS 200 and the load 122 in the standby mode. In the illustrated embodiment, the plurality of solid line connections represent a plurality of active (e.g., powered-energized) connections, while the plurality of dashed line connections represent a plurality of inactive (e.g., powered-off (deenergized)) connections.

As discussed above with respect to act 306, no power is provided to the output 204 in the standby mode of operation. The power received at the input 202 is provided to the charger 206, and the charger 206 charges the battery 210 with the power received from the input 202. The voltage regulator 208 senses the output of the charger 206 and communicates a plurality of voltage feedback signals to the charger 206 based on the sensed parameter.

The battery operation mode will now be described with reference to fig. 6. Fig. 6 illustrates the UPS 200 and the load 122 in the battery mode. In the illustrated embodiment, the plurality of solid line connections represent a plurality of active (e.g., powered-energized) connections, while the plurality of dashed line connections represent a plurality of inactive (e.g., powered-off (deenergized)) connections.

As discussed above with respect to act 312, because no acceptable power is available from the input 202, no power is provided from the input 202 during the battery mode of operation. The battery 210 provides stored DC power to the inverter 216, which inverter 216 converts the DC power to AC power and provides the AC power to the output 204 through the relay 212. The output 204 provides the AC power to the load 122 to power the load 122.

As discussed above, the load 122 may include a load capacitor 124 that stores reactive power. If the reactive power is not collected, the reactive power will eventually be wasted (e.g., dissipated as heat) and not utilized. Thus, in some embodiments, the inverter 216 is configured to periodically maintain the output of the inverter 216 at 0 to allow the load capacitor 124 to discharge the stored reactive power to the clamp charger circuit 214.

In some embodiments, the clamp charger circuit 214 may regulate the reactive power (e.g., transition the reactive power from a first voltage level to a second voltage level) and provide the regulated power supply to the battery 210 to charge the battery 210. The voltage regulator 208 monitors the output of the clamp charger circuit 214 and provides a voltage feedback signal to the clamp charger circuit 214. After the load capacitor 214 discharges a certain amount of power, or after a certain period of time has elapsed, the inverter 216 resumes supplying AC power from the battery 210 to the output 204.

The mains operation mode will now be described with reference to fig. 5. Fig. 5 shows the UPS 200 and the load 122 in the mains mode. In the illustrated embodiment, the plurality of solid line connections represent a plurality of active (e.g., powered-energized) connections, while the plurality of dashed line connections represent a plurality of inactive (e.g., powered-off (deenergized)) connections.

As discussed above with respect to act 314, in the mains mode of operation, power is provided from the input 202 to the output 204 and the charger 206. The controller 220 drives the relay 212 to connect the input 202 to the output 204 (e.g., in response to a plurality of control signals received from the controller 220). The charger 206 receives power from the input 202 and charges the battery 210 with the power received from the input 202. The voltage regulator 208 monitors the output of the charger 206 and provides a plurality of voltage feedback signals to the charger 206.

The clamp charger circuit 214 includes a connection coupled between the relay 212 and the output 204, and the clamp charger circuit 214 is configured to receive at least a portion of the power provided to the output 204 from the input 202. The clamp charger circuit 214 conditions the received power and provides the conditioned power to the battery 210 to charge the battery 210 in parallel with the charger 206.

For example, as discussed in more detail below with reference to FIG. 7, the clamp charger circuit 214 may be implemented using a DC/DC flyback circuit topology (topology). In some embodiments, the voltage regulator 208 is configured to sense an indicative parameter of the power provided by the clamp charger circuit 214 and provide a plurality of voltage feedback signals to the clamp charger circuit 214 based on the sensed parameter.

In alternative embodiments, the voltage regulator 208 may be disconnected from the clamp charger circuit 214 during the battery mode of operation. For example, the UPS 200 may include a switch 222, the switch 222 being coupled between the voltage regulator 208 and the clamp charger circuit 214. In some embodiments, the switch 222 may be maintained in an open and non-conductive position during the battery mode of operation, while in other embodiments, the switch 222 may be maintained in a closed and conductive position.

Thus, in contrast to the clamp circuit 114 discussed above with reference to fig. 1, the clamp charger circuit 214 is electrically active during the mains mode of operation. More specifically, in the mains mode of operation, the clamp charger circuit 214 is configured to charge the battery 210 in parallel with the charger 206. Transferring a portion of the charging load from the charger 206 to the clamp charger circuit 214 enables the battery 210 to charge at substantially the same rate as the battery 110 while achieving a charger (e.g., the charger 206) having a lower power rating than existing chargers (e.g., the charger 106).

For example, table 1 illustrates differences in an exemplary power supply specification for the charger 106, the charger 206, the clamp circuit 114, and the clamp charger circuit 214. In the example shown in table 1, the energy storage capacity of the battery 110 is substantially similar to the energy storage capacity of the battery 210.

TABLE 1

	Conventional UPS	The UPS is disclosed
			Charger power supply	15 Watts	5 Watts
Clamping circuit power supply	17 Watts	17 Watts
			Charging time	For 12 hours	For 12 hours

As shown in table 1, in at least one example, the power rating of the charger 206 is approximately 3 times less than the power rating of the charger 106, and the power rating of the clamp circuit 114 is approximately equal to the power rating of the clamp charger circuit 214. Despite the reduced power rating of the charger 206 as compared to the charger 106, and despite the substantially equal energy storage capacities of the battery 110 and the battery 210, both the battery 110 and the battery 210 may be charged within approximately 12 hours, with the clamp charger circuit 214 being used during the mains mode of operation.

The clamp charger circuit 214 will now be described in more detail with reference to fig. 7, which shows a block diagram of the clamp charger circuit 214. The clamp charger circuit 214 includes an input 700, a rectifier 702, a DC/DC flyback converter 704, and a control system 706, and the clamp charger circuit 214 is configured to be coupled to the output 204, the voltage regulator 208, the battery 210, the relay 212, and the controller 220.

The input 700 is coupled to the rectifier 702, and the input 700 is configured to be coupled to an external AC power source (e.g., through the relay 212 or the output 204). The rectifier 702 is coupled to the input 700 and the DC/DC flyback converter 704. The DC/DC flyback converter 704 is coupled to the rectifier 702 and the control system 706, and the DC/DC flyback converter 704 is configured to be coupled to the battery 210. The control system 706 is coupled to the DC/DC flyback converter 704, and the control system 706 is configured to be coupled to the voltage regulator 208 and the controller 220.

The input 700 is configured to receive an AC input signal and provide the AC input signal to the rectifier 702. The rectifier 702 provides full-wave rectification (full-wave rectification) to the AC input signal to produce a rectified signal (RECTIFIED SIGNAL), and the rectifier 702 provides the rectified signal to the DC/DC flyback converter 704. In some embodiments, the input 700 may accept a DC input signal (e.g., DC reactive power discharged from a load capacitor) and provide the DC input signal to the rectifier 702, the rectifier 702 providing the DC input signal to the DC/DC flyback converter 704.

The DC/DC flyback converter 704 converts the rectified signal from a first voltage level to a second voltage level, and the DC/DC flyback converter 704 provides the converted signal to the battery 210 to charge the battery 210. The control system 706 controls the operation of the DC/DC flyback converter 704 based at least in part on a plurality of communication signals received from the voltage regulator 208 and the controller 220.

For example, the voltage regulator 208 may provide a plurality of voltage feedback signals to the control system 706 that are indicative of an output of the clamp charger circuit 214. The controller 220 may provide a plurality of control signals to the control system 706, including, for example, a clamp charger activation signal to turn on (turn on) the clamp charger circuit 214.

Fig. 8 illustrates a circuit diagram of the clamp charger circuit 214, according to one embodiment. The clamp charger circuit 214 includes the input 700, the rectifier 702, the DC/DC flyback converter 704, and the control system 706. The clamp charger circuit 214 is configured to be coupled to the output 204, voltage regulator 208, the battery 210, the relay 212, and the controller 220.

The rectifier 702 includes a diode bridge rectifier (diode bridge rectifier) 800 and a filter capacitor 802. The DC/DC flyback converter 704 includes a resistor 804, a first flyback capacitor 806, a first flyback diode 808, a transformer 810, a second flyback capacitor 818, and a second flyback diode 820. The transformer 810 includes a primary winding (PRIMARY WINDING) 812, a first secondary winding (secondary winding) 814, and a second secondary winding 816. The control system 706 includes a pulse width modulation (Pulse Width Modulation) controller 822, a supply capacitor 824, a switch 826, a first optocoupler 828, and a second optocoupler 830.

The diode bridge rectifier 800 is coupled to the input 700, the filter capacitor 802, the resistor 804, and the primary winding 812. The filter capacitor 802 is coupled to the diode bridge rectifier 800, the resistor 804, and the primary winding 812 at a first terminal, and the filter capacitor 802 is coupled to a reference terminal (e.g., a ground terminal) at a second connection.

The capacitor 804 is coupled to the diode bridge rectifier 800, the filter capacitor 802, and the primary winding 812 at a first connection, and the capacitor 804 is coupled to the first flyback capacitor 806, the cathode of the first flyback diode 808, the PWM controller 822, and the power supply capacitor 824 at a second connection. The first flyback capacitor 806 is coupled to the resistor 804, the cathode of the first flyback diode 808, the PWM controller 822, and the power supply capacitor 824 at a first connection, and the first flyback capacitor 806 is coupled to the first secondary winding 814 and a reference terminal at a second connection.

The flyback diode 808 is coupled to the resistor 804, the first flyback capacitor 806, the PWM controller 822, and the power supply capacitor 824 at a cathode connection, and the flyback diode 808 is coupled to the first secondary winding 814 at an anode connection. The primary winding 812 is coupled to the diode bridge rectifier 800, the filter capacitor 802, and the resistor 804 at a first connection, and the primary winding 812 is coupled to the switch at a second connection.

The first secondary winding 814 is coupled to the anode of the first flyback diode 808 at a first connection, and the first secondary winding 814 is coupled to the capacitor 806 and a reference terminal at a second connection. The second secondary winding 816 is coupled to the anode of the second flyback diode 820 at a first connection, the second secondary winding 816 is coupled to the second flyback capacitor 818 and a reference terminal at a second connection, and the second secondary winding 816 is configured to be coupled to the battery 210 at the second connection.

The second flyback capacitor 818 is coupled to the cathode of the second flyback diode 820 at a first connection, and the second flyback capacitor 818 is configured to be coupled to the battery 210 at the first connection. The second flyback capacitor 818 is also coupled to the second secondary winding 816 at a second connection, and the second flyback capacitor 818 is configured to be coupled to the battery 210 at the second connection. The second flyback diode 820 is coupled to the second secondary winding 816 at an anode connection, the second flyback diode 820 is coupled to the second flyback capacitor 818 at a cathode connection, and the second flyback diode 820 is configured to be coupled to the battery 210 at the cathode connection.

The PWM controller 822 is coupled to the resistor 804, the first flyback capacitor 806, the cathode of the first flyback diode 808, and the power supply capacitor 824 at a first connection, the PWM controller 822 is coupled to a reference terminal at a second connection, the PWM controller 822 is coupled to the second optocoupler 830 at a third connection, the PWM controller 822 is coupled to the first optocoupler 828 at a fourth connection, and the PWM controller 822 is coupled to a control terminal of the switch 826 at a fifth connection.

The power capacitor 824 is coupled to the resistor 804, the first flyback capacitor 806, the cathode of the first flyback diode 808, and the PWM controller 822 at a first connection, and the power capacitor 824 is coupled to a reference terminal at a second connection. The switch 826 is coupled to the primary winding 812 at a first connection, the switch 826 is coupled to a reference terminal at a second connection, and the switch 826 is coupled to the PWM controller 822 at a control connection.

The first optocoupler 828 is coupled to the PWM controller 820 at a first connection, the first optocoupler 828 is configured to be connected to a reference voltage source at a second connection, and the first optocoupler 828 is configured to receive a plurality of voltage feedback signals from the voltage regulator 208. The second optocoupler 830 is coupled to the PWM controller 822 at a first connection, the second optocoupler 830 is coupled to a reference terminal at a second connection, and the second optocoupler 830 is configured to receive an activation signal from the controller 220.

The clamp charger circuit 214 is generally configured to operate as follows. An AC input power is received at the input 700 and provided to the diode bridge rectifier 800. The diode bridge rectifier 800 rectifies the input AC power and provides the rectified power to the primary winding 812 of the transformer 810. The filter capacitor 802 assists in rectifying by filtering the rectified power signal. As discussed in more detail below, current flows through the primary winding 812 when the switch 826 is in an off and conductive position.

As the current supplied to the primary winding 812 increases, the magnetic energy stored in the transformer 810 increases. A positive voltage is induced at the plurality of non-dotted terminals of the first secondary winding 814 and the second secondary winding 816 relative to the plurality of non-dotted terminals of the first secondary winding 814 and the second secondary winding 816 in response to an increase in stored magnetic energy.

Due to the negative polarity of the first secondary winding 814 and the second secondary winding 816, the first flyback diode 808 and the second flyback diode 820 are reverse-biased. Thus, no current passes through the first secondary winding 814 and the second secondary winding 816. The first flyback capacitor 806 and the second flyback capacitor 818 discharge stored power to the power supply capacitor 824 and the battery 210, respectively, while the first flyback diode 808 and the second flyback diode 820 are reverse biased.

As the current supplied to the primary winding 812 decreases, the magnetic energy stored in the transformer 810 decreases. More specifically, the magnetic energy is released to induce a current in the first secondary winding 814 and the second secondary winding 816. The polarity from the first secondary winding 814 to the second secondary winding 816 is reversed and the first flyback diode 808 and the second flyback diode 820 become forward-biased.

The currents induced in the first and second secondary windings 814 and 816 are provided to the first and second flyback capacitors 806 and 818, respectively, to charge the first and second flyback capacitors 806 and 818. As understood by those of ordinary skill in the art, the charge voltage provided to the first flyback capacitor 806 and the second flyback capacitor 818 depends on the number of turns in the plurality of windings 812-816 of the transformer 810.

The current through the primary winding 812 is controlled by the switch 826, the switch 826 being coupled in series between the primary winding 812 and a reference terminal. The switch 826 is then controlled by the PWM controller 822. The PWM controller 822 communicates control signals to the switch 826 based at least in part on the voltage feedback signals received from the voltage regulator 208 via the first optocoupler 828 and on an activation signal received from the controller 220 via the second optocoupler 830. For example, in the event that the plurality of voltage feedback signals received from the voltage regulator 208 indicate that the output voltage provided by the transformer 810 to the battery 210 exceeds a target voltage, the PWM controller 822 may be configured to control the switch 826 to correct an overvoltage condition.

In addition, in the event that the controller 220 determines that the clamp charger circuit 214 should not be activated (e.g., during the standby mode of operation), the controller 220 may provide a deactivation signal to the second optocoupler 830. The PWM controller 822 may detect the driving of the second optocoupler 830 and provide a plurality of control signals to the switch 826 to disable current flow through the primary winding 812. Thus, the PWM controller 822 is operable to regulate the charging power provided to the battery 210 to about a desired level.

Fig. 9 shows a plurality of graphs 900 to illustrate the principles described above according to one embodiment. The plurality of graphs 900 includes a UPS enabled trace 902, a UPS input voltage trace (UPS input voltage trace) 904, and a battery charging current trace (battery charging current trace) 906. The UPS enable tracking 902 indicates a UPS enable signal, wherein a logic low signal (logical LOW signal) (e.g., represented by a "0" value) indicates that the UPS 200 is not capable of providing power to the output 204 and a logic high signal (logic HIGH SIGNAL) (e.g., represented by a "1" value) indicates that the UPS 200 is capable of providing power to the output 204.

The UPS input voltage trace 904 indicates a UPS input voltage level. For example, the UPS input voltage trace 904 may indicate a voltage received at the input 202 of the UPS 200. The battery charging current trace 906 indicates a UPS battery charging current. For example, the battery charging current trace 906 may indicate a current provided to the battery 210.

Using the UPS 200 as an example, at a first time 908, AC input power is provided to the input 202 of the UPS 200. As shown by the UPS input voltage tracking 904, the AC input power source is approximately sinusoidal. As shown by the UPS enabled tracking 902, the UPS 200 does not provide the AC power to the output 204 because the UPS 200 is not enabled at the first time 908.

At a second time 910, the charger 206 begins to provide a charging current to the battery 210 as shown by the battery charging current trace 906. In some examples, the charger 206 provides a charging current of approximately 320 milliamps, such as where the charger 206 has a 5 watt power rating. The clamp charger circuit 214 is not enabled at the second time 910. For example, because the controller 220 has not yet transmitted an enable signal to the second optocoupler 830, the clamp charger circuit 214 may not be enabled.

At a third time 912, the UPS 200 begins to provide power to the output 204 as indicated by the UPS enable tracking 902 transitioning a logic low level to a logic high level. For example, the UPS 200 may transition from a standby mode of operation to a utility mode of operation at the third time 912.

At a fourth time 914, the clamp charger circuit 214 begins to provide a charging current to the battery 210. In some examples, for example, where the charger 206 has a 5 watt power rating and the clamp charger circuit 214 has a 17 watt power rating, the charger 206 and the clamp charger circuit 214 collectively provide a charging current of about 1.25 milliamps. As discussed above, in some embodiments, the energy storage capacity of the battery 210 is such that the battery can be fully recharged by the 1.25 milliamp charging current in up to 12 hours.

In view of the above disclosure, it should be appreciated that an improved clamp charger circuit has been provided. The clamp charger circuit is operable to charge a battery (e.g., a UPS battery) in the mains operation mode and the battery operation mode. In the battery mode of operation, the clamp charger circuit recirculates recirculated reactive power stored in a load capacitance. In the mains mode of operation, the clamp charger circuit provides a charging current to the UPS battery in parallel with a primary battery charger.

In alternative embodiments, the clamp charger circuit may be configured for different operations. For example, the clamp charger circuit may be activated only during the battery mode of operation, or only during the mains mode of operation. During a first period of time, the clamp charger circuit may be configured to operate between the mains operation mode and the battery operation mode. During a second period of time, the clamp charger circuit may be configured to operate only during one mode of operation.

Thus, with the implementation of the clamp charger circuit, the power rating of the primary battery charger may be reduced because the primary battery charger is not the only source of a charging current. Reducing the power requirements of the first battery charger allows a smaller and cheaper battery charger to be implemented.

Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the invention should be determined from proper construction of the claims and their equivalents.

Claims

1. A method of operating an uninterruptible power supply, comprising: the method comprises the following steps:

in a first mode of operation, receiving AC power at an input of the uninterruptible power supply;

in the first mode of operation, providing the AC power to a charger and a clamp charger circuit;

Charging an uninterruptible power supply battery of the uninterruptible power supply with a first charging current from at least a portion of the AC power source through the charger in parallel with the clamp charger circuit in the first mode of operation;

Charging the uninterruptible power supply battery with a second charging current from at least a portion of the AC power source through the clamp charger circuit in parallel with the charger in the first mode of operation;

Providing output power from the ups battery at an output of the ups in a second mode of operation; and

Charging the uninterruptible power supply battery with a third charging current through the clamp charger circuit in the second mode of operation, wherein a load capacitor included in a load is configured to store a reactive power, and in the second mode of operation an output of an inverter is periodically held at 0 to allow the load capacitor to discharge the stored reactive power to the clamp charger circuit such that the clamp charger circuit charges the uninterruptible power supply battery with the reactive power.

2. The method of claim 1, wherein: the method further comprises the steps of: an indication parameter of the first charging current and the second charging current in the first operating mode is sensed by a voltage regulator.

3. The method of claim 2, wherein: the method further comprises the steps of: generating a plurality of feedback signals by the voltage regulator based on the sensed parameters, and controlling the clamp charger circuit based on the plurality of feedback signals.

4. A method as claimed in claim 3, wherein: the method further comprises the steps of: the second charging current and the third charging current are regulated by the clamp charger circuit based on the plurality of feedback signals.

5. The method of claim 1, wherein: the method further comprises the steps of: in the second mode of operation, power is received at the output of the uninterruptible power supply.

6. The method of claim 5, wherein: receiving power at the output of the uninterruptible power supply includes receiving power discharged from a load capacitor.

7. The method of claim 1, wherein: charging the uninterruptible power supply battery includes charging the uninterruptible power supply battery with the third charging current from at least a portion of the output power supply.

8. An uninterruptible power supply system, characterized by: the uninterruptible power supply system includes:

An input configured to receive an input AC power source;

an output configured to provide output AC power to a load, wherein the load comprises a load capacitor to store a reactive power;

A battery charger coupled to the input and configured to be coupled to a battery, the battery charger configured to:

in a first mode of operation, receiving a first portion of the input AC power from the input; and

In the first mode of operation, providing a first charging current to the battery, the first charging current from the first portion of the input AC power source;

a clamp charger circuit coupled to the output terminal and the battery; and

An inverter coupled to the battery;

Wherein the clamp charger circuit is configured to:

in the first mode of operation, receiving a second portion of the input AC power from the input;

In the first mode of operation, providing a second charging current to the battery in parallel with the battery charger providing the first charging current to the battery, the second charging current from the second portion of the input AC power source;

in a second mode of operation, providing power from the battery to the load; and

In the second mode of operation, charging the battery includes periodically maintaining an output of the inverter at 0 to allow the load capacitance to discharge the stored reactive power to the clamp charger circuit so that the clamp charger circuit charges the battery using the reactive power.

9. The uninterruptible power supply system of claim 8, wherein: the clamp charger circuit is further configured to receive power from a load capacitor at the output in the second mode of operation.

10. The uninterruptible power supply system of claim 8, wherein: the uninterruptible power supply system further includes a voltage regulator coupled to the battery charger and the clamp charger circuit.

11. The uninterruptible power supply system of claim 10, wherein: the voltage regulator is configured to sense an indicative parameter of the first charging current and the second charging current in the first mode of operation.

12. The uninterruptible power supply system of claim 11, wherein: the voltage regulator is further configured to generate a plurality of feedback signals based on the sensed parameter and to communicate the plurality of feedback signals to the clamp charger circuit.

13. The uninterruptible power supply system of claim 12, wherein: the clamp charger circuit is a DC/DC flyback converter.

14. The uninterruptible power supply system of claim 13, wherein: the DC/DC flyback converter includes:

an input configured to receive an input power;

an output configured to be coupled to the battery;

A transformer coupled between the input end and the output end, the transformer comprising a primary winding;

A switch coupled in series with the primary winding;

at least one optocoupler configured to be coupled to the voltage regulator; and

A pulse width modulation controller coupled to the at least one optocoupler and to the switch.

15. The uninterruptible power supply system of claim 14, wherein: the pulse width modulation controller is configured to:

receiving the plurality of feedback signals from the at least one optocoupler;

Generating a plurality of switching signals based on the plurality of feedback signals; and

The plurality of switching signals are provided to the switch to control a current through the primary winding.

16. The uninterruptible power supply system of claim 15, wherein: controlling the current through the primary winding includes controlling an output current provided by the transformer to the output.

17. An uninterruptible power supply system, characterized by: the uninterruptible power supply system includes:

An input configured to receive an input AC power source;

a clamp charger circuit coupled to the output terminal and the battery;

an inverter coupled to the battery;

A plurality of means for charging the battery in the first mode of operation using the clamp charger circuit in parallel with the battery charger;

Wherein the clamp charger circuit is configured to:

18. The uninterruptible power supply system of claim 17, wherein: the uninterruptible power supply system further includes means for receiving DC power from the load in a second mode of operation.

19. The uninterruptible power supply system of claim 18, wherein: the plurality of means for charging the battery includes a plurality of means for:

In the first mode of operation, receiving a second portion of the input AC power from the input; and

In the first mode of operation, a second charging current is provided to the battery, the second charging current from the second portion of the input AC power source.

20. The uninterruptible power supply system of claim 17, wherein: the uninterruptible power supply system further includes means for providing a third charging current to the battery in the second mode of operation, the third charging current being from the battery.